Cone crushers, insofar as the material upon which they operate is concerned, are generally of two types, "standard" or "coarse" head and "fine" or "short" head. The former is used for larger material and possesses greater reduction ability than does the latter which is designed to produce finer material, something the coarse head type cannot efficiently accomplish. Two of the distinguishing characteristics of the coarse head crusher are the greater slant height of its head and the larger included angle between its mantle and bowl liner in order to accommodate larger material and to reduce it quickly. The fine or short head crusher is literally that, having a head whose slant height is less than that of the coarse head crusher as well as a smaller included angle between its mantle and bowl liner.
In the past, in order to alter a cone crusher from coarse to fine operation, the practice has been to replace the entire head and its mantle with a shorter head and mantle, as well, of course, to replace the bowl liner and frame. This, obviously, is an elaborate and time consuming operation, normally done in the field. One could, of course, have separate coarse and fine head crushers on hand, and this is not unusual in the case of smaller crushers, say, 36 inches, but in the case of the larger ones, say, 72 inches, that is usually a prohibitively expensive alternative inasmuch as a fine head is not needed nearly as often as a coarse head. There are other disadvantages, too. Besides requiring a lot of time and the need to have separate heads on hand in the field, the change from coarse to fine head, or vice versa, necessarily involves lifting the entire head out of the crusher and thus exposing its bearings to the entrance of grit and debris. Finally, not only the contractor in the field but also the manufacturer must suffer the expense and inconvenience of additional inventory by having to keep two types of heads in stock. Hence, the primary object of the present invention is to provide means by which the need, particularly in the case of the larger crushers, to change heads from coarse to fine or vice versa is eliminated, thus reducing time and inventory expense and avoiding bearing contamination.